The Zähringer in the 12th century used the title of Duke of Zähringen, in compensation for having conceded the title of Duke of Swabia to the Staufer in 1098.
The "Duchy of Zähringen" (Herzogtum Zähringen) by definition consisted of the territories and fiefs held by the Zähringer, and it was not seen as a duchy in equal standing with the old stem duchies. The Zähringer attempted to expand their territories in Swabia and Burgundy into a
fully recognized duchy, but their expansion was halted in the 1130s due to their feud with the Welfs. They were granted the special title of Rector of Burgundy in 1127, and they continued to use both titles until their extinction in 1218.
Pursuing their territorial ambitions, they founded numerous cities and monasteries, on either side of the Black Forest as well as in the western Swiss plateau.

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The earliest known ancestor of the family was one Berthold, Count in the Breisgau (d. 982), who was first mentioned in 962. In view of his name, he may have been related to the Alemannic Ahalolfing dynasty.

Berthold's son Berthold II (c. 1050–1111), who like his father fought against Henry IV, inherited a lot of the lands of Rudolf's son Count Berthold of Rheinfelden in 1090 (though not his comital title, which stayed with the family von Wetter-Rheinfelden). Berthold II is so named both as Duke of Swabia (following Berthold of Rheinfelden, the first duke of Swabia of this name) and as head of the House of Zähringen (following his father, who is counted as Berthold I of Zähringer in spite of not historically having used the name Zähringen).
Berthold II did use the "Zähringen" name, although he moved his main residence from Zähringen Castle to the newly-built Freiburg Castle in 1091.

In 1092, Berthold II was elected Duke of Swabia against Frederick I of Hohenstaufen. In 1098, he reconciled with Frederick, renounced all claims to Swabia and instead concentrated on his possessions in the Breisgau region, assuming the title of Duke of Zähringen.
He was succeeded in turn by his sons, Berthold III (d. 1122) and Conrad (d. 1152).

In 1127, upon the assassination of his nephew Count William III, Conrad claimed the inheritance of the County of Burgundy against Count Renaud III of Mâcon. Renaud prevailed, though he had to cede large parts of the eastern Transjuranian lands to Conrad, who thereupon was appointed by Emperor Lothair III as a "rector" of the Imperial Kingdom of Arles or Burgundy. This office was confirmed in 1152 and held by the Zähringen dukes until 1218, hence they are sometimes called "Dukes of Burgundy", although the existing Duchy of Burgundy was not an Imperial but a French fief. Duke Berthold IV (d. 1186), who followed his father Conrad and founded the Swiss city of Fryburg (today's Fribourg-Freiburg) in 1157, spent much of his time in Italy in the train of Emperor Frederick I Barbarossa.

His son and successor, Berthold V, showed his prowess by reducing the Burgundian nobles to order. This latter duke was the founder of the city of Bern (1191), and when he died in February 1218, the ducal line of the Zähringen family became extinct. Among other titles, the Zähringen family acted as Reichsvogt of the Zürichgau area.

After the extinction of the ducal line in 1218, much of their extensive territory in the Breisgau and modern-day Switzerland returned to the crown, except for their allodial titles, which were divided between the counts of Urach (who subsequent called themselves the Counts of Freiburg) and the counts of Kyburg, both descended from the sisters of Berthold V. Less than fifty years later, the Kyburgs died out and large portions of their domains were inherited by the House of Habsburg. Bern achieved the status of a free imperial city, whereas other cities such as Fribourg-Freiburg only obtained the same status later in history.

Territories of the dominant noble houses in Swabia and Upper Burgundy around 1200; Zähringen possessions shown in green

Berthold I (ancestor of both the House of Zähringen and the House of Baden) held the comital titles of Breisgau, Thurgau, as well as being reeve in Stein am Rhein (owned by the bishop of Bamberg).
The county of Thurgau was lost in c. 1077.
Berthold II, founder of the House of Zähringen proper, in 1098 received Zähringen castle and
the jurisdiction over Zürich (alongside the Counts of Lenzburg until 1173).
Ownership of the county of Rheinfelden and of Burgdorf also dates to c. 1198.
The "rectorate" of the county of Burgundy was granted in 1127 (inheritance of Otto-William, Count of Burgundy). Ownership of Burgundy was contested, and Zähringer de facto rule was
limited to the parts of Upper Burgundy east of the Jura and north of Lake Geneva. The territories south of Lake Geneva were conceded to the Savoy and Provence in 1156. In compensation, Berthold IV received the investiture right for the bishops of Geneva, Sion and Lausanne, de facto realised only in the case of Lausanne.
The extinction of the counts of Lenzburg in 1173 strengthened the Zähringer position south of the Rhine,
but their territorial expansion was halted following their support of the Welfs in the unsuccessful feud against Conrad III of Germany during 1138–1152, and frustrated their ambitions to carve out a contiguous territorial duchy wedged between Swabia and Burgundy, in spite of late attempts on the part of Berthold V to increase his territorial sway (who as late as 1210 aimed at receiving the jurisdiction over St. Gallen).

Instead of territorial expansion, the dukes of Zähringen from the 1150s focussed on attaining more immediate feudal control over the territories they already had. This included their policy of expanding settlements into fortified towns or cities and the construction of new castles, mostly in their territories north of the rhine, while their encroachment on the rights of the comital nobility south of the Rhine seems to have been resisted, mostly passively but in the case of the
lords of Glâne and Thun in an open revolt in 1191.

Zähringen attributed arms in a stained glass window by Hans Reichle (c. 1570–1642) in Freiburg town hall. There are two traditions of attributed arms, either or an eagle displayed gules (shown here) or gules a lion rampant or, based on the respective coats of arms used in the later medieval period by the counts of Freiburg who claimed the Zähringer inheritance (the houses of Fürstenberg and Schönborn).[2]

Berthold II, Duke of Carinthia, Margrave of Verona (c. 1000–1078, r. 1061–1077) is also known as "Berthold I of Zähringen", and therefore the succession of dukes of Zähringen begins with his son as Berthold II: